diff --git a/src/applications/phortune/editor/PhortuneMerchantEditEngine.php b/src/applications/phortune/editor/PhortuneMerchantEditEngine.php
--- a/src/applications/phortune/editor/PhortuneMerchantEditEngine.php
+++ b/src/applications/phortune/editor/PhortuneMerchantEditEngine.php
@@ -112,6 +112,7 @@
         ->setDescription(pht('Initial merchant members.'))
         ->setConduitDescription(pht('Set merchant members.'))
         ->setConduitTypeDescription(pht('New list of members.'))
+        ->setInitialValue($object->getMemberPHIDs())
         ->setValue($member_phids),
 
     );
diff --git a/src/applications/transactions/editfield/PhabricatorEditField.php b/src/applications/transactions/editfield/PhabricatorEditField.php
--- a/src/applications/transactions/editfield/PhabricatorEditField.php
+++ b/src/applications/transactions/editfield/PhabricatorEditField.php
@@ -401,8 +401,15 @@
 
   public function setValue($value) {
     $this->hasValue = true;
-    $this->initialValue = $value;
     $this->value = $value;
+
+    // If we don't have an initial value set yet, use the value as the
+    // initial value.
+    $initial_value = $this->getInitialValue();
+    if ($initial_value === null) {
+      $this->initialValue = $value;
+    }
+
     return $this;
   }